Microwave processing of ceramics

Book · Sun Dec 31 04:00:00 EST 1995

OSTI ID:182753

Johnson, D L; Skamser, D J; Su, H ^[1]

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1. Northwestern Univ., Evanston, IL (United States)

The widespread use of microwave systems for food processing has fueled an enthusiastic search for applications of MW energy to the processing of materials, particularly ceramics and polymers. Success has come slowly because of the nature of the interaction of MW radiation with solid materials. In many instances the dielectric loss exhibits a sharp rise with rising temperature, leading to thermal instability and runaway. The authors have modeled microwave heating and demonstrated both the cause of thermal runaway and procedures to circumvent it. Some form of hybrid heating, in which the material is heated both by surface heating and MW energy, is required when thermal runaway is a problem. The authors have investigated sintering, both with and without a plasma, reaction bonding of silicon nitride (RBSN), and chemical vapor infiltration (CVI) synthesis of ceramic matrix composites using MW heating. The sintering rate of alumina in a plasma excited either by microwaves or induction coupling (5 MHz) is significantly greater than with conventional heating. The enhancement is believed to be caused by the creation of excess point defects by the plasma. Experimental and modeling results of these two processes will be presented.

• OSTI ID: 182753
• Report Number(s): CONF-950612--; ISBN 0-7803-2669-5
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM OXIDES
CHEMICAL VAPOR DEPOSITION
COMPOSITE MATERIALS
EXPERIMENTAL DATA
IMPREGNATION
MATHEMATICAL MODELS
MICROWAVE HEATING
SILICON NITRIDES
SINTERING
THEORETICAL DATA